It rests to be seen if Mesiab Labs will get the approval for the mark retweet granted because there might be a lot of objections to the application, not only from Twitter, who now seem to be in a unique position to claim the mark, but also from competitors such as Tweetmeme. Funnily enough, the whole RT concept is just another Twitter community driven and created component and it seems ironic at least if someone were able to claim the mark for a concept or term which is owned by the Community.